The present invention relates to a wheel bearing of a motor vehicle, with a wheel hub arranged rotatably on a transmission axle via at least one pair of rolling bearings and having a flanged surface for at least one running wheel, and with a brake disc connected to the wheel hub.
There is already a wheel mounting of a driven axle, with a hollow axle body which receives the wheel loads and on the respective outer end of which is seated, fixed axially, at least one rolling bearing carrying a wheel hub with at least one brake disc or brake drum, to which wheel hub is flanged a drive-shaft flange of a drive shaft projecting out of the respective outer end of the hollow axle body, the drive-shaft flange and the wheel hub and also the wheel hub and the flange or flanged region of the brake disc or brake drum having in each case contacting mounting surfaces.
The object on which the present invention is based is to design and arrange a wheel hub in such a way that simple mounting of the brake disc and of the rolling-bearing arrangement is ensured.
The object is achieved, according to the present invention, in that the wheel hub is of two part or multi-part design, a first wheel-hub part being connected to a first rolling bearing and/or to a second rolling bearing and a second wheel-hub part being connected to the brake disc. What is achieved thereby is that, when the brake disc is being changed, there is no need to also remove the bearing arrangement. The brake disc can be demounted together with the second wheel-hub part, while the first wheel-hub part having the bearing arrangement remains on the transmission axle designed as an axle journal. This affords advantages even during the assembly of the wheel bearing, because, for example, the bearing arrangement can be prefabricated, so that later, during line assembly, all that is necessary is a substantially less time-consuming attachment or screwing-on of the second bearing part together with a brake disc. It is also conceivable to screw-connect the brake disc additionally, independently of the wheel hub, in a similar way to motorcycles, so that only the brake disc may be mounted, independently of the wheel hub.
For this purpose, it is advantageous that the brake disc has a flanged part forming an axial bearing surface or a flanged surface and a radial bearing surface and be designed as a cylindrical basic body, the inside diameter of the flanged part and of the brake disc being at least equal to the outside diameter of the first wheel-hub part. This ensures that the brake disc, together with the second bearing part, can be separated from the first bearing part or, during mounting, can be slipped over the first wheel-hub part. The second wheel-hub part is in this case arranged in front of the first wheel-hub part, so that the latter can likewise be drawn off outwards after the release of the screw connection.
According to another embodiment, an additional possibility is that the basic body of the brake disc is formed by the second wheel-hub part and the radial bearing surface is formed by the first wheel-hub part and/or by the second wheel-hub part, the flanged surface of the brake disc being oriented radially to, and the basic body coaxially to, a wheel-bearing center axis. This ensures a simple and rapid production of the flanged surfaces.
Furthermore, it is advantageous that the first wheel-hub part has a flanged surface designed as a radial bearing surface and/or as an axial bearing surface for the second wheel-hub part, the first wheel-hub part being connected to the second wheel-hub part via a screw connection. This likewise ensures simple and rapid manufacture. The screw connection serves at the same time for connecting a drive shaft to the wheel hub.
It is also advantageous, for this purpose, that the first wheel-hub part and/or the second wheel-hub part are/is connected to the brake disc via at least one fixing screw and/or via at least one bolt. The fixing screw serves in this case for the premounting of the second wheel-hub part and the brake disc, so that these can be connected as a structural unit to the first wheel-hub part. A sufficient fastening of the brake disc to the second or else the first wheel-hub part is afforded by the bolt connection for the running-wheel connection.
Finally, according to a preferred embodiment of the present invention, there is provision for there to be provided at the outer end of the transmission axle an axle flange of a drive shaft, the axle flange being designed as a shaft flange and being connected to the first wheel-hub part and/or to the second wheel-hub part via the screw connection of the two wheel-hub parts. Both wheel-hub parts are thus connected to the drive flange simultaneously via only one screw connection.
It is particularly important for the present invention that the first and the second rolling bearing are connected at the outer end of the transmission axle to a prestressing element designed as an axle nut or are prestressed by the prestressing element. The bearing prestress of the rolling-bearing arrangement can thus be determined independently of the mounting of the brake disc.
It is also advantageous that the brake disc has a further radial bearing surface and/or a parking brake together with the axle journal, the ratio of the distances in the axial direction from an axial bearing surface to a brake-disc surface and from the axial bearing surface to the parking brake being between 2:1 and 10:1. The brake disc surface is consequently arranged so as to be offset to the rear with respect to its fastening flange and is connected in one piece to the fastening flange via a flanged part. In addition to the possibility of being able to arrange a parking brake within this flanged part, the cylindrical basic-body surface affords an additional cooling surface for the brake disc.
In connection with the design and arrangement according to the present invention, it is advantageous that the individual bolts of the screw connection are arranged on a part-circle of the size of the mean circumference of the wheel hub. The screw connection connects both wheel-hub parts and by virtue of its rotationally-symmetrical arrangement can be handled simply and quickly.
Moreover, it is advantageous that, after the release of the bolting connection for the rim, the running wheel or the rim is separated from the hub and, after the release of the screw connection of the shaft flange, the drive shaft, together with the second wheel-hub part and the brake disc, is separated from the remaining part of the wheel bearing or of the first wheel-hub part. In this case, it is advantageous that, after the release of the fixing screws, the brake disc is separated from the second wheel-hub part and, after the exchange of the brake disc, the latter is reconnected to the second wheel-hub part by the fixing screws. The two parts are slipped onto the wheel bearing or the first wheel-hub part and are connected to this and to the drive shaft by the screw connection. Only then is the running wheel, together with the brake disc, fastened via the bolt connection.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.